MAINT: Update required numpy version
TST: Also test numpy 1.7
MAINT: Remove unused import.
TST: Replace self.assertTrue(np.array_equal... with npt.assert_array_equal.

The former wouldn't work in numpy <=1.7 (before this fix https://github.com/numpy/numpy/commit/6dc709a5aa0b17b5a74b7456d7cbd2580d9063f6#diff-297f089c1998527812c2b0d9975afa0d)
MAIN: Remove unused import
TST: Same thing in PERMANOVA as in...
... dac1bcfad0f0483f9f5725bb5b8938bfaafdc28
Merge pull request #252 from Jorge-C/1.7

np 1.7